Power to the people...!

[cooder]

My stab at making a powersupply for pedalboard that goes on wallwart and can be used with rechargable battery pack.

Time to make pcb: 3 weeks twiddling the thumbs, doin' nothing but waiting for slow boat from China.
It's a buck converter I scored off ebay, with voltage display. Regulates voltage down to level that can be adjusted with trimpot.

Time to wire up internal parts like jacks to pcb: probably 15 min....

Time to do the ruler kung-fu, layout the holes to fit the pcb parts, file square hole, put the jacks in, prepare accentuator, wire battery pack and fiddle it all in place to work: considerably longer...

Anyway, here's the idea: I feed it around 15 to 16 V DC via wallwart or rechargable Li-Ion pack, the buck converter regulates it down to 9.4 V (or where I set the trimpot to) and Bob's your Uncle (that's probably a typical Kiwi saying for 'its all sweet' or so).

How long would the battery pack last?
Well, the proof is in da pudding, as they say.
Of course depends on currentdraw of board, capability of batteries and efficiency of converter. The batteries I scored (off ebay, Chinese) are labelled an unrealistic 6000mAh a pop, that is way inflated dream lala land stuff and I don't think it would be even possible to make a 186500 rechargable that capable, so rather than calculating screwed figures I just stick it together and see what happens.

Really neat about the converter is that it has the voltage display AND a little pcb mini switch that allows to select between displaying output voltage (default setting; 9.4 V), input voltage (meaning it monitors battery charge; fully charged set does 16.2 V) or, even better, toggles between input and output voltage display every 3 seconds. So it shows input (battery level) and output level (to pedals).
VERY useful to monitor when batteries are starting to loose the plot and get a feel for how long it will last.
To accentuate that switch I had a stompswitch accentuater from a broken momentary switch (guess who..... Tayda....) that I modified to put in there to switch the display modes. It was a bit of a challenge to get the accentuator to fit right to get that tiny pcb switch... but it worked in the end.
I left a tiny hole to be able to reach trimpot if needed, once all in place I stuck a clear foil over cutouts so that dust and gunk doesn't go in too easily.

Does it work?
So far so good, I don't notice any elevated noise levels with the buck converter (and I have used it once on high volume at band practise so far), it works fine on wallwart (a 15V digital switching wart) and last about 7 to 8 hours on battery charge as it seems, in my setup.
My board that I'm supplying has 20 different circuits from wah, tuner, overdrives, two delays and the most powerhungry ones probably the Harbinger, Doppelgaenger Phaser and Octaver on there.

I do have a second battery pack, so I can take it to gig and have a spare one at hand if needed and I could always go to wallwart too if push comes to shove,
So it seems a good solution so far (although I'm keen to see what RobA comes up with his other approach in the eagle thread too!).

Will post another photo if you guys are interested with the whole thing mounted to pedalboard.

[jimilee]

Well that is cool. I'd love to see it in action and how it reacts with that many pedals plugged in.

[jubal81]

Now that's a really neat project. Nice to know that the unit puts out a steady voltage despite a decreasing input voltage. A low power indicator would be the balls.


One other thing I'm curious about is if it would be ore efficient with the batteries in parallel using a boost converter ...

[cooder]

Now that's a really neat project. Nice to know that the unit puts out a steady voltage despite a decreasing input voltage. A low power indicator would be the balls.


One other thing I'm curious about is if it would be ore efficient with the batteries in parallel using a boost converter ...

Cheers. The low power indicator is basically the voltage display.
If the batteries drop to 12 V it gets close, at 11 V it goes too low to provide steady 9.4 V output (the input voltage has to be 1.5 V above desired output). This works better than a low indicator light as it is more specific.

RobA seems to be working on something to regulate up that has a very high efficiency.

[RobA]

Looks cool. The level indicator is nice.

I've got one big question, is the brand name on those Li-Ion batteries really UltraFire? .

I really like the idea of being able to use both wall wart and a battery pack as the input voltage. It makes it so much less risky to use.

I wouldn't expect that you'll get many issues from the buck converter. It's how the DC Brick works for example and it's a pretty efficient way to do the voltage regulation.

[cooder]

Looks cool. The level indicator is nice.

I've got one big question, is the brand name on those Li-Ion batteries really UltraFire? .

I really like the idea of being able to use both wall wart and a battery pack as the input voltage. It makes it so much less risky to use.

I wouldn't expect that you'll get many issues from the buck converter. It's how the DC Brick works for example and it's a pretty efficient way to do the voltage regulation.

Cheers Rob, so far it works good and seeing that I seem to get up to 8 hours of use out of a charge it's not too bad for my requirements. I have the feeling I could confidently take this to a full gig without staring all the time at the voltage display... especially if I have the backup second battery pack and a wallwart handy too. The voltage drops only very slowly when fully charged, in  fact I think two full gigs would be possible on one charge.

Yes the batteries have really the clever name "UltraFire", doh...
You find those on ebay, often used in high output LED torches etc.

[Thomas_H]

My first comment is: Great job!
I didnt have time to read the technical data but I will later.

:-)

Ok, thats a nice concept but I dont see how you recharge the battery block in your setup or am I missing something?

[RobA]

My first comment is: Great job!
I didnt have time to read the technical data but I will later.

:-)

Ok, thats a nice concept but I dont see how you recharge the battery block in your setup or am I missing something?

I was guessing it's an external charger. That way, one set can be used while a second set is charging.

[cooder]

My first comment is: Great job!
I didnt have time to read the technical data but I will later.

:-)

Ok, thats a nice concept but I dont see how you recharge the battery block in your setup or am I missing something?

I was guessing it's an external charger. That way, one set can be used while a second set is charging.

Bingo! We've got a Bingo.....

[blearyeyes]

Good one Cooder!  Innovative idea.

[chuckbuick]

That's a cool idea you've put into action.  Well done.